Moderate M1.1 solar flare erupts at 00:21 UTC on October 16, 2025

A moderate M1.1 solar flare erupted at 00:21 UTC on October 16, 2025.

This M1.1 flare was recorded with a start time of 00:17 UTC, peaking at 00:21 UTC, and ending at 00:24 UTC, originating from active region 4246. Today’s flares include additional C-class flares and an M1.3 flare (peaking at 14:08 UTC, region 4246). Multiple C-class events, primarily from region 4246, were also observed.

In 24 hours to 12:30 UTC on October 16, solar activity remained at moderate levels due to several M-class flares, including an M1.1 eruption. Region 4246 was the primary source, alongside contributions from region 4248. Several associated coronal mass ejections (CMEs) and continued spot development were also noted.

Solar Activity Forecast calls for a likelihood of minor to moderate (R1-R2) radio blackouts through October 18, with a slight chance for an isolated R3 (Strong) event due to ongoing M-class flare activity.

Active sunspot regions presently observed on the Earth-facing solar disk include AR 4246 (N22W56 – Beta-Gamma-Delta), AR 4248 (N07W27 – Beta-Gamma-Delta), AR 4250 (N07W21 – Alpha), AR 4252 (S13E28 – Beta), and AR 4254 (N10E60 – Alpha).

Over the past 24 hours, the greater than 2 MeV electron flux reached high levels, with a peak of 2 850 pfu. Proton flux above 10 MeV remained at background levels. The greater than 2 MeV electron flux is expected to decrease to normal to moderate levels with CME arrivals and return to higher levels on October 17–18. There is a slight chance of a solar radiation storm at the S1 – Minor level through October 18.

Solar wind parameters gradually returned to nominal levels as a negative coronal hole high-speed stream waned. The interplanetary magnetic field remained at or below 6 nT, with solar wind speeds decreasing from about 520 km/s to 450 km/s. Disturbed solar wind conditions are expected by late October 16 and will continue through October 18 due to CME arrivals from eruptions on October 11–13 and October 15.

Geomagnetic field activity was mostly quiet. G2 – Moderate geomagnetic storm levels are expected late on October 16 due to CME influences, with G1 – Minor geomagnetic storm activity likely to continue into October 17–18 from recent solar eruptions.